Perioperative Morbidity and Outcomes in Pediatric Patients Transitioned From Extracorporeal Membrane Oxygenation to Ventricular Assist Device Support: A Study of the Society of Thoracic Surgeons Congenital Heart Surgery Database

As a bridge to transplant strategy, children transitioned from extracorporeal membrane oxygenation (ECMO) to ventricular assist device (VAD) have higher waitlist mortality compared with those who receive de novo VAD. However, the contribution of the immediate perioperative period and differences in the two groups are not well studied. We performed a nested case-control study between children receiving de novo VAD (group 1) and those transitioned from ECMO to VAD (group 2) between 2014 and 2019 using The Society of Thoracic Surgeons (STS) database. A total of 735 children underwent VAD placement with 498 in group 1 and 237 in group 2. Patients in group 2 were significantly younger, smaller, and significantly sicker, were twice as likely to transition to biventricular VAD and need unplanned reoperations. Overall mortality was 16% for group 1 and 34% for group 2 ( p < 0.01). Regression analysis showed that ECMO use (odds ratio [OR], 2.17 [1.3-3.4]), ventilator need (OR, 2.2 [1.3-3.9]), and cardiogenic shock (OR, 1.8 [1.2-2.8]) were all independent preoperative predictors of VAD mortality while dialysis need (OR, 25.5 [8.6-75.3]), stroke (OR, 6.2 [3.1-12.6]), and bleeding (OR, 1.9 [1.1-3.4]) were independent postoperative predictors of VAD mortality within 30 days (all p < 0.05). The study demonstrated significant baseline differences between the two cohorts, warranting avoidance of comparison. Early elective VAD placement in this cohort of patients should be sought to avoid interim ECMO and high post-VAD mortality.

The role of ventricular assist device in children

The first and successful implantation of a ventricular assist device in 1990 has allowed an 8-year-old child with an end-stage heart failure to undergo a heart transplantation. This milestone paved the way to consider support with ventricular assist in the armamentarium of heart failure management in infants, children and adolescents. Several systems have evolved and faded owing to unacceptable complications. Indications and contraindications to implantation have been established. Anticoagulation management is still on its way to impeccability. Despite the challenges, issues and concerns revolving around ventricular assist devices, the system definitely supports pediatric patients with end-stage heart failure until heart transplantation and could allow recovery of the myocardium.

Parental responsibility for pediatric ventricular assist devices: Views of families on the acceptability of hospital discharge

BACKGROUND

Paracorporeal pediatric VAD therapy requires hospital residency due to device and patient factors. Discharge home is potentially possible with a mobile driving unit. This study aimed to investigate family views on hospital discharge of a child on VAD.

METHODS

Qualitative methodologies were adopted. We undertook 24 interviews of families who had a transplanted child previously on a VAD, and participant observations of two families who were current VAD patients residing in hospital.

RESULTS

Families experienced overwhelming emotions as they spent time adjusting to the diagnosis, the need for transplant, family separation, and financial concerns. Despite many parents being partially/fully trained on the VAD, the majority would be reluctant to be discharged, fearing emergencies, high burden of care needs, and social isolation. Three families with a child on a Berlin Heart expressed willingness to reside in the hospital accommodation at least part-time, to facilitate private family time. One child on HeartWare was discharged home, with another going through the discharge process. Discharge was not acceptable to most families if this meant downgrading their child's transplant listing urgency status.

CONCLUSION

Parents and children on VAD value independence and some private family time but not at the perceived expense of safety. Families preferred their child on VAD to remain resident in hospital even if mobility is improved with a mobile driving device. Parental education should acknowledge the high burden on families, risks of a remote setting and offer intermediate residency options. It cannot be assumed families want hospital discharge.

Pediatric ventricular assist device therapy for advanced heart failure-Hong Kong experience

Ventricular assist devices (VADs) are life-saving options for children with heart failure unresponsive to medical therapy as a bridge to transplantation or cardiac recovery. We present a retrospective review of 13 consecutive children who underwent implantation of VAD between 2001 and 2018 in our center. The median age was 12 years (1-17 years), weight was 45 kg (10-82 kg). Etiologies of heart failure were dilated cardiomyopathy (CMP) (n = 8), myocarditis (n = 2), ischemic CMP (n = 1), restrictive CMP (n = 1) and congenital heart disease (n = 1). Pre-implantation ECMO was used in 5, mechanical ventilation in 4, renal replacement therapy in 2 and IABP in 1. Devices used were: Berlin Heart EXCOR left VAD (LVAD), biventricular VAD (BIVAD) (n = 5, 2), CentriMag LVAD, BIVAD (n = 1, 2), HeartWare (n = 2), HeartMate II (n = 1). Median duration of support was 45 days (3-823 days). Overall survival was 85%. Four patients were successfully bridged to transplantation, 2 died while on a device, 4 remain on support and 3 were weaned from VAD. Late death occurred in 2 transplanted patients. Complications included bleeding requiring reoperation in 1, neurologic events in 3, driveline infections and pericardial effusion in 2 each. In one patient, CentriMag BIVAD provided support for 235 days, which is longest reported duration on such a VAD in the Asia Pacific region. Survival for pediatric patients of all ages is excellent using VADs. Given the severity of illness in these children morbidity and mortality is acceptable. VADs could potentially be used as a long-term bridge to transplantation in view of the donor shortage in the pediatric population.

Ambulatory Intravenous Inotropic Support and or Levosimendan in Pediatric and Congenital Heart Failure: Safety, Survival, Improvement, or Transplantation

End-stage heart failure (HF) frequently needs continuous inotropic support in hospital and has high morbidity and mortality in absence of heart transplantation. This study reports outcome, efficacy, and safety of continuous ambulatory inotropes (AI) and/or periodic levosimendan (LS) infusions in pediatric HF patients. The study included 27 patients, median age 9.4 (0.1-26.1) years, with severe HF (6 myocarditis, 13 dilated cardiomyopathy, 2 restrictive cardiomyopathy, 6 repaired congenital heart disease). Dobutamine and milrinone AI were administered in 21 patients through a permanent central catheter for median duration 1.0 (0.3-3.7) years. Additionally, 14 AI patients and the remaining 6 study patients received periodic LS infusions for median duration 1.1 (0.2-4.2) years. During median follow-up 2.1 (0.3-21.3) years, 4 patients died of worsening HF after 0.8-2.1 years AI, 6 patients underwent heart transplantation with only 3 survivors, while the rest remained stable out of the hospital with complications 4 line infections treated with antibiotics and 4 catheter reinsertions due to dislodgement. Severe pulmonary hypertension was reversed with AI in 2 patients, allowing successful heart-only transplantation. Therapy with AI was discontinued after 1.4-0.4 years in 6 improved myocarditis and 3 cardiomyopathy patients without deterioration. In conclusion, prolonged AI and/or LS infusions in HF are safe and beneficial even in small infants, allowing stabilization and reasonable social and family life out of the hospital. It may provide precious time for heart transplantation or myocardial remodeling, improvement, and possible discontinuation even after long periods of support.

Role of paediatric assist device in bridge to transplant

Background

While heart transplantation has gained recognition as the gold standard therapy for advanced heart failure, the scarcity of donor organs has become an important concern. The evolution of surgical alternatives such as ventricular assist devices (VADs), allow for recovery of the myocardium and ensure patient survival until heart transplantation becomes possible. This report elaborates the role of VADs as a bridge to heart transplantation in infants and children (≤18 years old) with end-stage heart failure.

Methods

A retrospective review of the medical records of 201 heart transplant recipients between May 1986 and September 2014 identified 78 children [38.8%; mean age 7.2 (7.8±6.0) years old; IQR: 2.6-11.8 years] with advanced heart failure who were supported with a VAD [left VAD (LVAD) =21; biventricular VAD (BVAD) =57] as a bridge to heart transplantation. Fourteen (17.9%) patients were less than 1 year old; 15 (19.2%) children had a cardiac arrest and underwent cardiopulmonary resuscitation, with 7 of these patients also requiring extracorporeal membrane oxygenation (ECMO) support prior to implantation of a VAD. The aetiology of heart failure was primarily cardiomyopathy (dilative, restrictive from endocardial fibrosis, idiopathic or toxic-induced), reported in 56 (71.8%) patients. The VADs employed were primarily Berlin Heart EXCOR^® (n=63), HeartWare (n=13), Berlin Heart INCOR^® (n=1), and Toyobo (n=1).

Results

Mean duration of VAD support was 59 (133.37±191.57) days (range, 1-945 days; IQR: 23-133 days) before a donor heart became available. The primary complication encountered while patients were being bridged to transplant was mediastinal bleeding (7.8%). The main indication for pump exchanges was thrombus formation in the valves. There was no incidence of technical failure of the blood pump or driving system components. Skin infections around the cannulae occurred in 2.5%. Adverse neurological symptoms (thromboembolism 11.1%, cerebral haemorrhage 3.6%) that occurred did not have any permanent neurological sequelae that could be detected on clinical examination in this study. Mean duration of follow-up was 9.4 (10.3±7.6) years (IQR: 3.74-15.14 years). Cumulative survival rates of patients bridged to transplantation with VAD were 93.6%±2.8%, 84.6%±4.1%, 79.1%±4.7%, 63.8%±6.2%, 61.6%±7.1%, and 52.1%±9.3% at 30 days, 1, 5, 10, 15 and 20 years, respectively. There was no statistically significant difference (P=0.79) in survival rates of patients bridged to heart transplantation with VAD compared to those who underwent primary heart transplantation. Post-transplant survival rates stratified according to the type of VAD implanted and number of ventricles supported were not statistically different (P=0.93 and 0.73, respectively). In addition, post-transplant survival rates were not significantly different when age, gender and diagnosis were adjusted for. Furthermore, no statistically significant difference was found when post-transplant survival rates of children who had episodes of rejection were compared to those who did not have episodes of rejection.

Conclusions

The results in this series demonstrate that VADs satisfactorily support paediatric patients with advanced heart failure from a variety of aetiologies until heart transplantation. The data further suggests that patients bridged with VADs have comparable long-term post-transplant survival as those undergoing primary heart transplantation.

Paracorporeal Lung Devices: Thinking Outside the Box

Extracorporeal Membrane Oxygenation (ECMO) is a resource intensive, life-preserving support system that has seen ever-expanding clinical indications as technology and collective experience has matured. Clinicians caring for patients who develop pulmonary failure secondary to cardiac failure can find themselves in unique situations where traditional ECMO may not be the ideal clinical solution. Existing paracorporeal ventricular assist device (VAD) technology or unique patient physiologies offer the opportunity for thinking "outside the box." Hybrid ECMO approaches include splicing oxygenators into paracorporeal VAD systems and alternative cannulation strategies to provide a staged approach to transition a patient from ECMO to a VAD. Alternative technologies include the adaptation of ECMO and extracorporeal CO₂ removal systems for specific physiologies and pediatric aged patients. This chapter will focus on: (1) hybrid and alternative approaches to extracorporeal support for pulmonary failure, (2) patient selection and, (3) technical considerations of these therapies. By examining the successes and challenges of the relatively select patients treated with these approaches, we hope to spur appropriate research and development to expand the clinical armamentarium of extracorporeal technology.

Concomitant Pulsatile and Continuous Flow VAD in Biventricular and Univentricular Physiology: A Comparison Study with a Numerical Model

Introduction

To develop and test a lumped parameter model to simulate and compare the effects of the simultaneous use of continuous flow (CF) and pulsatile flow (PF) ventricular assist devices (VADs) to assist biventricular circulation vs. single ventricle circulation in pediatrics.

Methods

Baseline data of 5 patients with biventricular circulation eligible for LVAD and of 5 patients with Fontan physiology were retrospectively collected and used to simulate patient baselines. Then, for each patient the following simulations were performed: (a) CF VAD to assist the left ventricle (single ventricle) + a PF VAD to assist the right ventricle (cavo-pulmonary connection) (LCF + RPF); (b) PF VAD to assist the left ventricle (single ventricle) + a CF VAD to assist the right ventricle (cavo-pulmonary connection) (RCF + LPF)

Results

In biventricular circulation, the following results were found: cardiac output (17% RCF + LPF, 21% LCF + RPF), artero-ventricular coupling (-36% for the left ventricle and -21.6% for the right ventricle), pulsatility index (+6.4% RCF + LPF, p = 0.02; -8.5% LCF + RPF, p = 0.00009). Right (left) atrial pressure and right (left) ventricular volumes are decreased by the RCF + LPF (by RPF + LCF). Pulmonary arterial pressure decreases in the LCF + RPF configuration. In Fontan physiology: cardiac output (LCF + RPF 35% vs. 8% in RCF + LPF), ventricular preload (+4% RCF + LPF, -10% LCF + RPF), Fontan conduit pressure (-5% RCF + LPF, +7% LCF + RPF), artero-ventricular coupling (-14% RCF + LPF vs. -41% LCF + RPF) and pulsatility (+13% RCF + LPF, - 8% LCF + RPF).

Conclusions

A numerical model supports clinicians in defining and innovating the VAD implantation strategy to maximize the hemodynamic benefits. Results suggest that the hemodynamic benefits are maximized by the LCF + RPF configuration.

End-organ recovery post-ventricular assist device can prognosticate survival

BACKGROUND

This study examines our institutional ventricular assist devices (VADs) experience over two decades to understand trends towards predictors of mortality.

METHODS

Retrospective study of patients aged 0-21years supported with a VAD from January 1996 to May 2015. Patient data was examined pre and post-VAD implant among survivors and non-survivors.

RESULTS

Thirty-six patients identified (8 supported by Thoratec® VAD and 28 supported by EXCOR Berlin Heart®). Patient's diagnosis included dilated cardiomyopathy (DCM) (n=19,53%), congenital heart disease (CHD) (n=12,33%), and other (n=5,14%). Median age and body surface area (BSA) were 1.0years[0-7years] and 0.41[0.24-0.92], respectively. Survival to discharge was 75% with no deaths with DCM. The survival rate for patients with CHD was 42%. Univariate analysis showed diagnosis of CHD, smaller BSA and respiratory failure post-implant (Intermacs criteria) as risk factors for mortality. Median duration of VAD support was lower in non-survivors, 14 vs 63days (p=0.03). Renal function at time of transplant or death was normal/pRIFLE Risk category in 20(74%) of survivors and 2(22%) of non-survivors (p=0.06). Post-implant, peak total bilirubin in the first week trended lower in survivors (p=0.06).

CONCLUSIONS

Persistent end-organ impairment in the first 2weeks after VAD placement could be a useful prognostic marker for survival to transplant.

Application of a Lumped Parameter Model to Study the Feasibility of Simultaneous Implantation of a Continuous Flow Ventricular Assist Device (VAD) and a Pulsatile Flow VAD in BIVAD Patients

The aim of this work is to develop and test a lumped parameter model of the cardiovascular system to simulate the simultaneous use of pulsatile (P) and continuous flow (C) ventricular assist devices (VADs) on the same patient. Echocardiographic and hemodynamic data of five pediatric patients undergoing VAD implantation were retrospectively collected and used to simulate the patients' baseline condition with the numerical model. Once the baseline hemodynamic was reproduced for each patient, the following assistance modalities were simulated: (a) CVAD assisting the right ventricle and PVAD assisting the left ventricle (RCF + LPF), (b) CVAD assisting the left ventricle and PVAD assisting the right ventricle (LCF + RPF). The numerical model can well reproduce patients' baseline. The cardiac output increases in both assisted configurations (RCF + LPF: +17%, LCF + RPF: +21%, P = ns), left (right) ventricular volumes decrease more evidently in the configuration LCF + RPF (RCF + LPF), left (right) atrial pressure decreases in the LCF + RPF (RCF + LPF) modality. The pulmonary arterial pressure slightly decreases in the configuration LCF + RPF and it increases with RCF + LPF. Left and right ventricular external work increases in both configurations probably because of the total cardiac output increment. However, left and right artero-ventricular coupling improves especially in the LCF + RPF (-36% for the left ventricle and -21% for the right ventricle, P = ns). The pulsatility index decreases by 8.5% in the configuration LCF + RPF and increases by 6.4% with RCF + LPF (P = 0.0001). A numerical model could be useful to tailor on patients the choice of the VAD that could be implanted to improve the hemodynamic benefits. Moreover, a model could permit to simulate extreme physiological conditions and innovative configurations, as the implantation of both CVAD and PVAD on the same patient.